+10 dB = ×10 intensity

🔊 Decibel

Slide along the decibel scale from a falling leaf to a jet engine and see what the logarithm hides: intensity ratios, safe listening time by the NIOSH rule, why 60 dB + 60 dB is only 63 dB, and how loudness drops with distance.

dB 85 dB

Intensity vs 0 dBI/I₀ = 10^(dB/10)

Pressure vs 0 dBp/p₀ = 10^(dB/20)

vs 60 dB speechtimes the intensity

Safe listening (NIOSH)

Add two sources

dB + dB = 63 dB

Distance fall-off

dB @ m → m =

Decibels compare intensities on a log scale: dB = 10·log₁₀(I/I₀), with I₀ = 10⁻¹² W/m² the threshold of hearing. Every +10 dB multiplies intensity ×10 but only sounds roughly twice as loud; every +3 dB doubles intensity and HALVES the NIOSH safe-listening time from 8h at 85 dB.